Shears



Patented Sept. 6, 1938 UNITED STATES PATENT OFFICE Claims.

My invention relates to improvements in shears.

The object of my invention is to provide shears for use in cutting heavy materials.

More particularly stated, it is the object of my invention to provide shears mounted upon a bed and equipped whereby to advance the shearing members mechanically and positively between shearing operations.

In the drawing:

Figure 1 is a side elevation of my shears with the parts in position at the close of a shearing operation.

Figure 2 is a view similar to Fig. 1, but with the parts in position for a shearing operation.

Figure 3 is a perspective of the lower portion of the movable blade extension and showing the parts associated with the bed of my shearing mechanism.

Like parts are designated by the same reference characters throughout the several views.

I have shown my shears or walking shears, as I have sometimes called them, in operation upon a heavy sheet Ill of sheet metal and in Figs. 1 and 2, the sheet metal is engaged between an oscillatable blade II and a non-oscillatable blade I2, the edges of which are suitably sharpened in accord with standard practice in the trade. When the oscillatable blade II is closed toward the other blade I2, which I shall hereafter term the fixed blade, there is a natural tendency for the sheet I0 to be thrust out of the bite of the blades. I therefore provide a work abutment I3 rigidly secured to a bed I4. It is operation.

The fixed blade I2 forms the forward tip of a bar I5 with a leg I6 supported by a pawl II which is in turn supported by a box-slide I8 in 40 slidable engagement with the bed I4. The pawl I1 is in pivotal relation to the slide I8 upon pin I9, and the leg I6 of the bar I5 is in pivotal relation to the pawl upon pin 20. The oscillatable shear blade I I-forms a part of a long lever 45 which is in pivotal relation to the bar I5 upon pivot pin 24. The bar 25 has a leg 26 supported upon a pawl 2! which in turn is supported upon a box-slide 28, pivot pins 29 and 30 performing the same oflice as that performed by the pivot pins I9 and 20 heretofore described.

At the rearward end of the bar I5 I provide a fulcrum pin upon which is mounted an operating handle 36 and a short lever 31, the parts 35, 35, and H being rigidly keyed or secured to gether to move as a unit. A link 38 mounted to upon this bed that my shears are mounted for rotate freely upon bolts 39 and 40 connects the lever 25 and the short lever 31.

Each of the pawls I1 and 21 is shaped as shown clearly in the drawing whereby to provide for frictional engagement of a point M with the bed I4 to resist and actually block movement in response to the tendency of the jaws or blades lI--I2 to slide off of the work sheet III. This tendency is assisted by springs 42 between the handles 43 of the pawls and the legs 26 or I6 with which they are associated.

A roller at 45 carried by the box-slide I8 assists in the free forward movement of the box-slide.

The operation of. my shears is as follows:

Assuming that the shears have completed a cutting operation upon the work sheet II] as shown in Fig. l, the operating handle 36 is swung to the position shown in Fig. 2 upon the fulcrum pin 35, thus oscillating the blade II about pin 24. This of course causes the leg 26 to oscillate to the position shown in Fig. 2 and since the pawl 21 in engagement at 40 with the bed I4 will not permit retrograde movement of the slide 28, the entire mechanism consisting of the bar I5 with its leg I6 and a box-slide I8 and all associated parts .are drawn forwardly, the point 48 of. the pawl I'I being slidably moved forwardly with the box-slide I8.

The operating handle 36 is then swung downwardly to accomplish the usual shearing operation and during this operation the pawl I'I prevents retrograde movement of the bar I5 and the forward oscillating movement of the leg 26 is permitted by the pawl 21, thus sliding the boxslide 28 forwardly while the actual cutting of the sheet I5 is taking place.

The cycle of operations is thus complete and the operating handle 36 may be repeatedly swung about fulcrum pin 35 to complete the shearing operation in a series of forward motions which may be likened to a walking sequence, advance of the relatively fixed blade I2 being accomplished between cutting or shearing operations.

I claim:

1. In a shearing mechanism having a base and relatively movable blades for advance with respect thereto, a dog for one of the blades to engage the base and prevent retrograde movement, and a dog for the other blade to prevent retrograde movement thereof, whereby in the relative movement of the blades to advance them relative to said base.

2. In a device of the character described, a base, a non-oscillatable shear blade having an extension toward said base, with a pawl for engagement with the base, an oscillatable blade for cooperation with the non-oscillatable blade and provided with an extension to said base and provided with a pawl for engagement therewith whereby in the movement of the oscillatable blade to advance the blades in the cooperative movement thereof.

3. In a shearing mechanism having a base and relatively movable blades for advance with respect thereto, a dog for one of the blades to engage the base and to prevent retrograde movement, and a dog for the other blade to prevent retrograde movement thereof whereby in the relaciated with a guide associated with said base.

4. In a shearing mechanism'having' a base and relatively movable blades for advance with respect thereto, said base having a guide associated with a dog for interengagement of the guide and the base, and means for interengagement of the dog and said blade whereby directional stresses imposed upon the blade will cause the dog to engage the base to prevent movement of the blade and said guide with reference to the base.

5. In a shearing mechanism having a base and relatively movable blades for advance with respect thereto, legs upon said blades, guides upon said base, each of said guides being provided with ...a. pivota11y mounted doggand each of said legs tive movement of the blades to advance them relative to said base, one of said dogs being aSSO-f being pivotally associated with one of said dogs "whereby in certain directional movements of said to engage the base. 

